Torque Sensor Structure with Dual Magnetic Yokes for Disturbance Rejection
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Solution Overview
Problem
Existing torque sensors are not robust against external disturbance fields, which is a significant challenge in applications like electric vehicles and industrial robotics where high currents can cause significant interference.
Innovation Solution
A sensor structure comprising a ring magnet with multiple poles and pairs of magnetic yokes with pads, where two magnetic sensors measure magnetic flux in opposite directions to determine and eliminate external disturbance signals, allowing for robust torque measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single magnetic sensor is used to detect magnetic flux density between magnetic yokes, then the device complexity is reduced, but the robustness against external disturbance fields deteriorates
Solution Approach 1:
The sensor structure is segmented into multiple independent magnetic yokes (first and second magnetic yokes) with respective gaps, allowing separate sensing channels. Each yoke-gap combination forms an independent measurement path, enabling differential sensing that cancels external disturbance fields while maintaining manageable complexity through modular design
Solution Approach 2:
Different regions of the sensor structure are assigned different functions: the first magnetic yoke with its gap forms one sensing channel while the second magnetic yoke with its gap forms another channel. This local differentiation allows each region to sense magnetic flux in a specific direction, enabling the system to distinguish between torque-induced flux and external disturbance fields through comparative analysis
2Reliability
If multiple discrete sensors are used to reduce external disturbance field influence, then the robustness against external disturbance fields is improved, but the device complexity increases
Solution Approach 1:
Multiple sensing functions are merged into a unified sensor structure where the first and second magnetic yokes with their respective gaps work together as an integrated system. The gaps are positioned to face opposite directions, allowing a single structural element to perform multiple sensing functions simultaneously, reducing overall complexity compared to separate discrete sensor assemblies
Solution Approach 2:
The magnetic yokes and gaps serve multiple functions: they guide magnetic flux from the magnet, provide sensing paths for torque measurement, and simultaneously act as disturbance rejection elements through their opposing gap orientations. This multi-functionality reduces the need for additional dedicated components, maintaining structural efficiency while achieving robust measurement
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides highly robust torque measurement insensitive to external disturbance fields, ensuring accurate readings in challenging environments.
Implementation Method 1
a ring magnet (M) mechanically connected or connectable to the first shaft (S1), and comprising a number of North and South poles alternatingly arranged at a circumference of the ring magnet
Implementation Method 2
a first magnetic sensor (S1) located in the first gap (G1) and configured for measuring at least one magnetic field component in the first gap (G1)
Data Source
Figure 1(a)~1(b)
Figure 1(c)~1(d)
Figure 2(a)~2(b)
AI summary
A sensor structure for measuring a torque applied to a first shaft and a second shaft interconnected by a torsion bar, comprising: a multi-pole ring magnet mechanically connected to the first shaft; two pairs of magnetic yokes (Y1, Y2 and Y3, Y4) mechanically connected to the second shaft, each yoke being connected to one or more pads by means of fingers; the fingers of the first pair of yokes (Y1, Y2) projecting mainly in a radial direction, the fingers of the second pair of yokes (Y3, Y4) projecting mainly in an axial direction; a first (C1, C2) and a second pair of flux collectors (C3, C4) with extensions forming a first and a second gap (g2); a first sensor in the first gap (g1), a second sensor in the second gap; a circuit for combining signals from the first and second sensor to reduce or eliminates the influence of an external disturbance field, and for determining the torque value.